weather file vs design day file in openstudio
What are the purposes for EPW files and DDY files in energy plus and Openstudio? When to I choose to use one or the other or both?
The DDY file is used for zone/system/plant sizing (design day simulation), while the EPW file (typically including hourly data for a year) is used for annual (a period) energy simulation.
The DDY file is in IDF format. You can copy and paste the objects in DDY file to IDF file.
@W. Chiang, Yes. You can import DDY file for system sizing without the EPW file. You need to modify the SimulationControl object as follow:
SimulationControl,
Yes, !- Do Zone Sizing Calculation
Yes, !- Do System Sizing Calculation
Yes, !- Do Plant Sizing Calculation
No, !- Run Simulation for Sizing Periods
No; !- Run Simulation for Weather File Run Periods
Thank you. I have another question, what's the difference between zone sizing and system sizing? I created a building with a single zone, and the design sensible cooling load in System Sizing I've got is roughly two times the size of the design sensible cooling load in Zone Sizing.